Which of the following is the most correct electron displacement for a nucleophilic reaction to take place?

Rank the hydrogen atoms $(H_a, H_b, H_c)$ in the following molecule according to their acidic strengths.

Match List $I$ with List $II$:

$(A)$. Inductive effect	$(I)$. Delocalization of $\pi$ electrons
$(B)$. Hyper-conjugation	$(II)$. Displacement of $\pi$ electrons
$(C)$. Resonance effect	$(III)$. Delocalization of $\sigma$ electrons
	$(IV)$. Displacement of $\sigma$ electrons

Choose the correct answer from the options given below:

In which of the following molecules do all the effects namely inductive,mesomeric and hyperconjugation operate?

State True or False for the following statements:
$(i)$ The stability of carbocation is explained by the delocalized structure of hyperconjugation.
$(ii)$ The stability of carbocation is explained by drawing the resonance structure.
$(iii)$ Hyperconjugation effect is $(+)$ or $(-)$.
$(iv)$ Mesomeric effect is $(+)$ or $(-)$.

In which of the following organic compounds are all effects (i.e.,mesomeric effect,hyperconjugation effect,and inductive effect) present?